Method and apparatus for drying a gas and chilling it to low temperatures

ABSTRACT

A method and apparatus are provided for continuously drying and chilling a high temperature, pressurized gas such as air to subzero temperatures. The high temperature pressurized gas is passed alternately through each of two parallel heat exchangers containing cooling coils through which cold refrigerant from a refrigeration system is passed. While one of the heat exchangers is being cooled by the cold refrigerant, the hot, pressurized gas is passed through it in heat exchange relationship with the cooling coils. Simultaneously, the other heat exchanger is cleared of moisture and other condensables by passing hot refrigerant gas from the compressor of the refrigeration system through its cooling coils. Before reversing the function of the heat exchangers, the flow of hot refrigerant gas to the one being defrosted is terminated and replaced with the flow of cold refrigerant to cool it in order to prevent carryover of moisture on changing stages of operation. A continuous flow of cooled, dried pressurized gas is obtained from the two heat exchangers and can be passed through a third heat exchanger provided with refrigerated coils to further chill the gas to sub-zero temperature. Prior to being passed to the third heat exchanger, the cooled gas from the two parallel heat exchangers can be cycled through a preliminary heat exchanger to effect pre-cooling of the entering hot, pressurized gas.

United States Patent 1 Peuchen et al.

[451 Aug. 7, 1973 METHOD AND APPARATUS rort DRYING A GAS AND CHILLING11' To Low TEMPERATURES [75] Inventors: Wilfred S. Peuchel, Wilmington;

Glenwood K. Pase, Whitehall, both of Del.

[73] Assignee: l'eucllel Inc Wilmington, Del.

[22] Filed: Mar. 1, 1972 [21] Appl. No.: 230,752

[52] 11.8. C1. ..,62/93,' 425/387, 62/150, 62/120, 62/272, 62/278,62/81, 62/324 [51] Int. Cl. F25b 43/00 [58] Field of Search 62/93,150,272, 62/95, 120, 278, 81; 425/387 8 [56] References Cited UNITEDSTATES PATENTS 2,867,988 1/1959 2,903,861 9/1959 2,960,840 11/ 19603,499,295 3/ 1970 3,500,497 3/1970 3,572,052 3/1971 Toth 62/278 FOREIGNPATENTS OR APPLICATIONS 642,948 6/1962 Canada 62/93 PrimaryExaminer-William .l. Wye

57 ABSTRACT A method and apparatus are provided for continuously dryingand chilling a high temperature, pressurized gas such as air to sub-zerotemperatures. The high temperature pressurized gas is passed alternatelythrough each of two parallel heat exchangers containing cooling coilsthrough which cold refrigerant from a refrigeration system is passed.While one of the heat exchangers is being cooled by the coldrefrigerant, the hot, pressurized gas is passed through it in heatexchange relationship with the cooling coils. Simultaneously, the otherheat exchanger is cleared of moisture and other condensables by passinghot refrigerant gas from the compressor of the refrigeration systemthrough its cooling coils. Before reversing the function of the heatexchangers, the flow of hot refrigerant gas to the one being defrostedis terminated and replaced with the flow of cold refrigerant to cool itin order to prevent carryover of moisture on changing stages ofoperation. A continuous flow of cooled, dried pressurized gas isobtained from the two heat exchangers and can be passed through a thirdheat exchanger provided with refrigerated coils to further chill the gasto sub-zero temperature. Prior to being passed to the third heatexchanger, the cooled gas from thetwo parallel heat exchangers can becycled through a preliminary heat exchanger to effect pre-cooling of theentering hot, pressurized gas.

9 Claims, 4 Drawing Figures 11 3,750,415 [4 1 Aug. 7; 1973 United StatesPatent [1 1 Peuchen et al.

7A 2 8 W 5 a ,4 Q w 4 u. f L M Q 2 p x i W l on M R 5 w l: w Wm w 3 n/ 9w w {.3 5 9 7 3 3 7 a 2 1/ Z v z v z 4 M v .v 2 m: 4 '1 1' a B Q 8 a *2o e a v v .ll 2 ,3 Al l 2 gi WWW- H 4. l v [0 H H H 9 a [I a w 2 11 m. vqlv PATENTEU AUG H975 SHEET 1 OF 2 METHOD AND APPARATUS FOR DRYING A GASAND CHILLING IT TO LOW TEMPERATURES This invention relates to animproved method and apparatus for chilling and removing moisture from ahot, pressurized gas such as air by directing the gas through heatexchangers containing cold refrigeration coils, whereby condensedmoisture is periodically removed from the heat exchangers withoutinterrupting the continuous function of the system and without requiringthe utilization of additional energy supplied from sources external tothe apparatus.

More specifically, the present invention is directed to an improvedmethod for providing a continuous flow of chilled, dried, pressurizedgas by passing a stream of hot, pressurized gas through one of a pair ofheat exchangers containing cooling coils which are chilled byrefrigerant from a refrigeration system containing compressor andcondenser means. Simultaneously with the passage of refrigerant throughthe first of the pair of heat exchangers to effect cooling and removalof condensables, the second of the pair of heat exchangers is cleared ofcondensed moisture by directing through its cooling coils aflow of hotrefrigerant gas directly from the compressor of the refrigerationsystem. Periodically the cycle is reversed so that the first heatexchanger is defrosted in this manner, while the coils of the secondheat exchanger are chilled and used to cool and remove condensables fromthe hot, pressurized gas now passing through it. ln this way both acontinuous flow of gas and continuous operation of the refrigerationcompressor are maintained. To prevent any carryover of moisture or othercondensables on changing cycles, transition stages are employed whereby,prior to switching the flow of pressurized gas from one heat exchangerto the other, the flow of hot refrigerant gas from the compressor intothe heat exchanger being defrosted is terminated, and a flow of coldrefrigerant from the refrigeration system is directed into its coilswhile, at the same time, pressurized gas continues to be passed over thechilled coils of the other heat exchanger.

Particularly in the blow-molding of plastics and similar procedures itis important to have a continuous flow of compressed, dry gas such asair available at a temperature of around 60 F. to use in chilling theinner surfaces of the blow-molded products. ,By chilling these plasticinner surfaces below the flow-point of the plastic, the removal of thearticle from the forming mold is facilitated, thereby increasing theproductivity of the mold by shortening the length of time the product isin the molding and setting stage. Further, by using a chilled,pressurized gas such as air it is possible to carry out the blow-moldingand chilling steps in a single step using the same gas for bothfunctions.

Various procedures and apparatus have been suggested for producing aflow of chilled, dry, pressurized gas suitable, for example, for use inthe abovedescribed manner in plastics blow-molding operations.Frequently, these systems enploy refrigerated heat exchangers to cooland remove moisture from the gas.

Accordingly, all these types of systems are faced with the problem ofremoving the condensed moisture at intervals from the heat exchangerunits.

In some devices, such as that described in U.S. Pat.-

No. 2,867,988 to Brandt, external electric power is supplied from timeto time to heating units to defrost the heat exchanger coils. This, ofcourse, involves an additional expenditure of power as well as theexpense of providing and maintaining the electrical heating systemitself. Other systems have required that the chilling and dryingoperation be periodically terminated to permit defrosting of the heatexchanger coils. Still other systems require the frequent cycling of therefrigeration compressors, thus shorteningtheir life expectancy andincreasing maintenance costs. As will be appreciated, each of theseprocedures has the disadvantage that they increase production costs bycausing delays and requiring added maintenance and expense.

It is accordingly a general object of the present invention to providean improved method and apparatus for producing chilled, dry, pressurizedgas.

It is another object of the present invention to provide an improved airdryer and chiller which operates continuously and permits removal ofcondensables from the apparatus without the need for externally suppliedheat energy or for interrupting the continuous chilling and drying ofgas passing through the system.

It is yet a further object of the present invention to provide a methodand apparatus for continuously chilling and drying pressurized gas bypassing it through chilled heat exchanger means which employ hotrefrigerant gas from the same refrigeration compressors used to providecold refrigerant to the heat exchangers to effect removal ofcondensables from the heat exchangers.

I It is still another object of the present invention to provide amethod and apparatus for chilling and drying of pressurized gas wherebyacontinuous flow of the pressurized gas is maintained byemployingparallel heat exchangers for chilling and removing water vaporand other condensables from the gas, which heat exchangers arealternately cooled by cold refrigerant and cleared of condensates by hotrefrigerant gas, both of which are provided by the refrigerationcompressor unit, which is operated continuously.

Another object of this invention is to provide a method and apparatusfor chilling and drying pressurized gas whereby a continuous cyclicsystem is employed which permits chilling and drying of the compressedgas and removal of condensables without any carryover of condensablesinto the chilled, dry, pressurized gas.

The method and apparatus of the present invention whereby theaforementioned and other objects are achieved will best be understoodand appreciated by reference to the accompanying drawings and thefollowing description thereof, which describes a specific embodiment ofthis invention.

FIGS. 1, 2 and 3 are block schematic diagrams which depict the cyclicoperationof the present invention.

FIG. 4 is a semi-schematic drawing with interior views showing thecomplete heat exchanger and refrigeration system of the presentinvention for cooling and drying pressurized air.

Reference is first made to FIGS. 1, 2, and 3 for an understanding of thefour-stage operation of the invention. High temperature, pressurized gasis supplied to the system by the externally located compressor 51. Inthe first stage, depicted in FIG. 1, high temperature, pressurized gasis passed through the heat exchanger A where moisture and othercondensables are condensed out of the gas by means of refrigerationcoils (not shown) cooled by refrigerant supplied by the compresset 52,and the condenser 54. Hot, compressed refrigerant gas from thecompressor 52, which is not directed to the condenser 54 issimultaneously passed into the refrigeration coils (not shown) of theheat exchanger B to melt ice and other condensables deposited when theheat exchanger is in the stage of operation in which it cools the hightemperature, pressurized gas. Both hot and cold refrigerant are returnedfrom the refrigeration coils of the heat exchangers, A and B, to thecompressor 52 by conduits which are not shown. Following cooling andremoval of condensables in the heat exchanger A, during the first stageof operation, the pressurizedgas leaves the heat exchanger and isintroduced into the heat exchanger C, which contains refrigeration coils(not shown) maintained at very low temperature (i.e., below F.) by meansof refrigerant from the compressor 53 and condenser 55. The dry,pressurized gas, which is cooled to a temperature of 60 F. emerges fromthe heat exchanger C in a continuous flow. Refrigerant from therefrigeration coils in the heat exchanger C is returned to thecompressor 53 by means of a suitable conduit, not shown. During thisfirst-stage operation, the heat exchanger B, which is being defrosted byhot refrigerant gas from the compressor 52, is by-passed by the flow ofpressurized gas through the system.

In the second stage of operation, shown in FIG. 2, the passage ofpressurized gas through the heat exchangers, A and C, continues as inthe first stage operation. The flow of hot refrigerant gas from thecompressor 52 into the refrigeration coils of the heat exchanger B isdiscontinued however, and instead, cold refrigerant from the condenser54 is passed into the coils of B to prevent any subsequent carryover ofmoisture when the pressurized'gas flow is changed from the heatexchanger A in the third stage.

During the third stage of operation, the functions of the heatexchangers, A and B, are exactly reversed from those of the first stage.As shown in FIG. 3, hot, pressurized gas from the compressor 51 isintroduced into the heat exchanger B where it is cooled and condensablesremoved by refrigeration coils cooled by refrigerant supplied from thecondenser 54. Simultaneously, the heat exchanger A is excluded from theflow of pressurized gas and is cleared of frozen condensables by meansof hot refrigerant gas from the compressor 54. The stream of chilled,pressurized gas emerges from the heat exchanger B and through the heatexchanger C, maintained at sub-zero temperature, from where it continuesto emerge in a continuous flow at a temperature of -60 F.

The fourth, and final, stage of operation is not shown in FIGS. 1, 2,and 3, but consists of a transitional precooling as in stage 2, beforereturning to stage 1. In stage 4, the flow of pressurized gas iscontinued through the heat exchangers, B and C, as in stage 3.Defrosting of the heat exchanger A is discontinued, however, byterminating the flow of hot refrigerant gas from the compressor 52.Instead, the heat exchanger A is pre-cooled by directing the flow ofrefrigerant from the condenser 54 into the refrigerant coils of A. Inthis stage, the cooling of the pressurized gas in the heat exchanger Bis continued by also directing the flow of refrigerant from thecondenser 54 into its refrigeration coils.

Referring now in detail to FIG. 4 for a more specific description of anembodiment of the present invention,

dual cylindrical, parallel heat exchangers are shown at l and 1A withcoils for carrying cold refrigerant shown within the cylindrical heatexchanger columns at 36 and 37, respectively. An additional heatexchanger, consisting of 6 parallel, horizontal, interconnectedcylinders, is shown at 3. Within each cylinder are coiled tubes, 38,which are interconnected and which carry cold refrigerant supplied fromthe condenser 7. Compressor 4 provides hot, pressurized gas through thepipe 25 into the condenser 6. Suitable liquid coolant is supplied to thecoils 41 within the condenser 6 and through the orifice 44 and removedthrough 43. This liquid coolant is cycled from a source not shown. Coldrefrigerant liquid is passed from the condenser 6 through pipe 27 to thesolenoid valves 10 and 12 which control the flow of cold refrigerantliquid, respectively, through the thermostatic expansion valves 16 and17. Alternately, pipe 26 provides for the direct passage of hot,pressurized refrigerant gas from the compressor 4 to the solenoid valves11 and 13. Cold refrigerant, after passing through the refrigerationcoils 36 and 37, is removed as gas from the top of the heat exchangers land 1A, respectively, by means of pipe 28 which returns the refrigerantto the compressor 4. Compressor 5 provides hot, compressed refrigerantgas through the pipe 29 to the condenser 7 where it is condensed intocold refrigerant liquid by a suitable coolant passing through theorifice 46 to the cooling pipes 42 and back out through 45 where it isrecycled and chilled by suitable circulating and cooling mechanisms notshown. Cold refrigerant liquid passes from the condenser 7 through thepipe 31 to the solenoid control valve 14 and the thermostatic expansionvalve 18, enters the heat exchanger 3 and is carried through the heatexchanger coils 38. The cold refrigerant is finally returned by means ofthe pipe 32 as gas to the compressor 5. Pipe 30 provides for directpassage of hot, compressed refrigerant gas to the solenoid valve 15 andthen into the heat exchanger pipe 38 for cycling through the heatexchanger coils 38 and return by pipe 32 to the compressor 5.

Valve means are provided at 19 for admitting into the system hot,pressurized air which is to be chilled and dried. An optionalpre-cooling cylinder isshown at 2 and provided with cooling coils 40. Apipe passes from the top of the pre-cooler 2 and divides into theseparate pipes, 20 and 21, which enter the bottom of the heat exchangersl and 1A. Additional pipes exit, respectively, at the top of each of theheat exchangers l and 1A and are each provided with the solenoid valves8 and 9, respectively. The pipes emerging from the top sides of the heatexchangers A and IA merge into pipe 22 which returns to the bottom ofthe pre-eooler where it is connected into the cooling coil 40. Pipe 23is connected at the exit end of the cooling coil 40 and conducts chilledair to horizontal heat exchanger 3. Pipe 24 provides for emergence ofthe cooled, dry, pressurized air from the heat exchanger 3 and leads tothe exit valve 39. Drains provided with valves are shown at 33 for theheat exchanger 1, at 34 for the heat exchanger 1A and at 35 for the heatexchanger 3.

In operation, high temperature, pressurized air is admitted from asource not shown through the valve 19 optionally into the pre-cooler 2where it is chilled by the cold air from heat exchanger 1 or IA,depending upon which of the solenoid valves, 8 and 9, are open orclosed, circulating through the coil 40. The pre-cooled, pressurized airthen emerges from the top of the precooler and alternately flows eitherthrough pipe 20 into heat exchanger 1 or pipe 21 into heat exchanger 1A,depending upon which of the solenoid valves, 8 and 9, are opened orclosed. A continuous flow of cold, chilled air is, however, maintainedfrom either the heat exchanger 1 or 1A through the pipe 22 where it isoptionally used to pre-cool fresh, incoming, high temperature,pressurized air in the pre-cooler 40 and then is passed through the pipe23 to the heat exchanger 3. In another embodiment of the invention, thepre-cooler 40 is dispensed with and the flow of chilled air from theheat exchanger 1 and 1A is directed immediately to the heat exchanger 3.

After final chilling in the heat exchanger 3 by means of coldrefrigerant passed through the coils 38, the subzero, pressurized airemerges through pipe 24 and valve 39.

Cold refrigerant is provided to the heat exchangers l and 1A from thecompressor 4 and the condenser 6 by means of pipes 25 and 27. Dependingupon whether the solenoid valve is open or closed, cold refrigerantliquid passes through the expansion valve 16 to the heat exchanger coils36 in the heat exchanger 1. Alternatively, the solenoid valve 10 isclosed and solenoid 12 open to provide the flow of cold refrigerantliquid through the expansion valve 17 to the coil 37 in the heatexchanger 1A. Cold refrigerant gas emerges from the respective coolingcoils of the heat exchangers 1 and 1A and is passed through the commontubing 28 back to the compressor 4. The refrigeration coils, 36 and 37,in the heat exchangers l and 1A through which cold refrigerant passes,provide the primary chilling of the high temperature air which is passedthrough the heat exchanger and also for the removal of condensables suchas water vapor from the air. These condensables are subsequently removedfrom the heat exchangers without interruption of the flow of air throughthe system by passing hot refrigerant gas directly from the compressor 4through the pipe 26 into the respective pairs of cooling coils, 36 and37. Control of this flow of hot refrigerant gas to cause defrosting ofthe coils is effected by means of the solenoid valves, 11 and 13.

During the first-stage operation, while cold refrigerant liquid is beingpassed through the pipe 27 to the expansion valve 16 and then into thecoil 36 of the heat exchanger 1, the solenoid valve 10 is open and thesoleniod valve 11 is closed. Simultaneously, the solenoid valve 12leading from heat exchanger 1A is closed but the solenoid valve 13controlling the flow of hot refrigerant gas through the pipe 26 is open,permitting hot refrigerant gas to flow through the cooling coils 37 inthe heat exchanger lA'. Condensables such as water are removed from therespective heat exchangers by means 0 valves 33 and 34 located at thebottom of the heat exchangers.

In the second stage of operation, both the solenoid 12 leading to theheat exchanger 1A and the solenoid 10 leading to the heat exchanger 1are opened while both solenoids 11 and 13 are closed, thereby excludingthe flow of hot, refrigerant gas from either heat exchanger 1 or 1A,while permitting the refrigeration coils 36 and 37 to be cooledsimultaneously by the flow of cold refrigerant from the condenser 6through the expansion valves 16 and 17.

Once the cooling coils 37 of the heat exchanger 1A are sufficentlychilled to prevent any carryover of moisture, the solenoid valve 8 isclosed and solenoid valve 9 opened, thereby causing the flow ofpressurized air from the pre-cooler 2 to be directed through pipe 21into heat exchanger 1A. At the same time, solenoid valve 10 is closed toexclude cold refrigerant from the cooling coils of heat exchanger 1.Solenoid valve 13 remains closed while 11 is opened so that hotrefrigerant gas from the compressor 4 defrosts the coils 36 of heatexchanger 1 in the same manner that heat exchanger 1A was previouslycleared of condensates removed from the hot, pressurized air.

At the completion of the third stage where hot, pressurized air ischilled and dried in heat exchanger 1A while heat exchanger 1B isdefrosted, the flow of hot refrigerant gas into the coils of heatexchanger 1 is terminated by closing solenoid valve 11. Simultaneously,solenoid valve 10 is opened causing a flow of cold refrigerant fromcondenser 6 through expansion valve 16 into the coils 36 of heatexchanger 1. The passage of air through the cooled heat exchanger 1A iscontinued during this pre-cooling of heat exchanger 1. Thus, the heatexchanger 1 is prepared for the return to the firststage operationwhereby it cools and removes moisture from the pressurized hot air whilethe heat exchanger 1A is defrosted in its turn by hot refrigerant gasfrom the compressor 4.

The flow of cooled, dried air which emerges alternately from the twoheat exchangers l and 1A flows on a continuous stream through pipe 22,either to the precooler 2 or directly to the heat exchanger 3 wherefinal chilling to 60 F. takes place.

Cooling is effected in the heat exchanger 3 by means of theinterconnected coils 38 through which passes cold refrigerant from thecondenser 7. While removal of condensables such as water vapor from theheat exchanger 3 is not frequently. required, due to its having beenpreviously eliminated from the air stream in the heat exchangers l and1A, occasionally the solenoid valve 14 is closed and solenoid valve 15opened so that, rather than cold refrigerant from the condenser, hotrefrigerant gas from the compressor 5 is directed into the coils 38 tofree them of accumulated frozen moisture.

Of course, it is within the scope of the present invention that severalpairs of heat exchangers and their cooling and defrosting means asherein described, can be employed in series. Thus, the single heatexchanger 3 could be replaced with a second pair of heat exchangers thesame as l and 1A and including cooling and defrosting means.

Activation of the various solenoid valves used to control the flow ofgases and liquids is accomplished by means of conventional electricalcircuits and relays which have not been shown. These circuits caninvolve largely manual control of the solenoids or can be extensivelyautomated to respond to timed signals for changing cycles, for example.

The expansion valves shown at 1 6, 17, and 18 in H6. 4 meter the amountof liquid refrigerant entering the respective heat exchangers tomaintain the predetermined temperature and pressure of the refrigerantgas. These valves are conventionally activated by means of sensors (notshown) which measure the temperature and pressure of the refrigerant gasafter it has absorbed heat from the gas being cooled.

The refrigeration components of the present invention, including thecompressors, condensers, expansion valves and refrigerant are, inthemselves, conventional in design and operation.

It is claimed:

1. An apparatus for continuously cooling and drying a pressurized gascomprising in combination first and second heat exchanger means adaptedfor cooling and condensing moisture from said pressurized gas; a thirdheat exchanger means adapted for further cooling and condensing moisturefrom the gas cooled and dried in said first and second heat exchangers;first and second refrigeration means operatively connected with and eachadapted to provide, in a cyclic system, to said first and second heatexchangers and to said third heat exchanger, respectively, separateflows of hot, pressurized refrigerant gas and cold refrigerant and toreceive a return flow of cold refrigerant gas from said heat exchangers;said first and second heat exchanger means being operatively disposed inparallel and each provided with operatively connected means forregulating and circulating alternating flows of hot refrigerant gas andcold refrigerant from said first refrigeration means through itself andreturning the gas to the refrigeration means; said third heat exchangermeans also being provided with means for regulating and circulatingalternate flows of hot refrigerant gas and cold refrigerant from saidsecond refrigeration means through itself and returning therefrigeration gas to the refrigeration means; said first and second heatexchanger means each being further provided with means operativelyconnected for alternately circulating and regulating a separate flow ofhigh temperature, pressurized gas through itself in heat exchangerelationship with said cold refrigerant and then to said third heatexchanger means where further circulating and regulating means areprovided for conducting said gas through said heat exchanger means inheat-exchange relationship with said cold refrigerant provided thereto.

2. The apparatus of claim 1 which further comprises preliminary heatexchanger means provided with means operatively connected with saidfirst and second heat exchangers for circulating the flow of cooled,high pressurized gas from said first and second heat exchangers throughitself and then to said third heat exchanger means; said preliminaryheat exchanger means being further provided with operatively disposedmeans for passing the stream of high temperature, pressurized gas fromits source in heat exchange relationship with said cooled gas and thento said first and second heat exchanger means.

3. The apparatus of claim 1 wherein said refrigeration means comprisesin combination condenser means and compressor means operativelyconnected to provide a flow of hot, compressed refrigerant gas to saidcondenser means and alternately gas from said compressor through thecooling coils of the second of said heat exchangers to melt substancespreviously condensed from the high pressure gas;

2. Terminating the flow of hot refrigerant gas from the compressorthrough ssid cooling coils of the second heat exchanger and replacing itwith a flow of cold refrigerant from the condenser while continuing toalso pass said cold refrigerant through the coils of said first of saidheat exchangers in heat exchange relationship with said high pressuregas introduced into said first heat exchanger; 3. Terminating the flowof high pressure gas into the first heat exchanger and directing itinstead into said second heat exchanger where it is passed through inheat exchange relationship cooling coils containing cold refrigerantfrom said refrigerant source; simultaneously terminating the flow ofcold refrigerant to the cooling coils of said first heat exchanger andpassing instead through said coils hot refrigerant gas from thecompressor to melt substances previously condensed from the highpressure gas; to each of'said first and second heat exchangers; saidcondenser means being further adapted to receive said hot, compressedrefrigerant from said compressor means and to condense and cool it to arefrigerant liquid; means operatively connected to said condenser forregulating and circulating said refrigerant liquid to each of said firstand second heat exchangers.

4. The apparatus of claim 1 wherein said hot, pressurized gas is airwhich emerges from said apparatus at a temperature below 0 F.

5. The apparatus of claim 4 wherein said air is cooled to F.

6. The apparatus of claim 1 which is operatively connected to providecold, pressurized air to a device for blow-molding plastic articles.

7. A four-stage continuous process for cooling hot, high pressure gascomprising the steps of:

1. Introducing said high pressure gas into one of two parallel heatexchangers and passing it through the heat exchanger in heat exchangerelationship with cooling coils containing a cold refrigerant suppliedfrom a refrigerant source which includes a compressor and acondenser,simultaneously passing hot refrigerant 4. Terminating the flowof hot refrigerant gas from the compressor through the cooling coils ofsaid first heat exchanger, and replacing it with a flow of coldrefrigerant from the refrigerant source while continuing to also passsaid cold refrigerant through the coils of said second heat exchanger inheat exchange relationship with said high pressure gas; said highpressure gas being removed from the two heat exchangers separatelyduring each of the four steps of the process and being continuouslycombined into a common stream and cooled further to sub-zero temperatureby being passed through a third heat exchanger provided with chilledrefrigerant from a refrigeration source.

8. The process of claim 7 wherein the hot refrigerant gas is pre-cooledin a preliminary heat exchanger in heat exchange relationship with thestream of gas carried off continuously from said heat exchangers whichis then directed to said third heat exchanger.

9. The process of claim 7 wherein said high pressure gas is air whichemerges from said third heat exchanger UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3,750,415 Dated August 7, 1973Inventor(s) W-i 1 Fred S Peuchen: Glenwood K. Pass It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Claim 3. s The apparatus of claim 1 wherein saidrefrigeration meanscomprises in combination condenser means and compressor meansoperatively connected to provide a flow of hot, compressed refrigerantgas to said condenser means and alternately to each of said first andsecond heat exchangers; said condenser means being further adapted toreceive said hot, compressed refrigerant from said compressor means andto condense and cool it to a refrigerant liquid; means operativelyconnected to said condenser for regulating and circulating saidrefrigerant liquid to each of said first and second heat exchangers.

Claim 7. A four-stage continuous process for cooling hot,

high pressure gas comprising the steps of:

1. Introducing said high pressure gas into one of two parallel heatexchangers and passing it through the heat exchanger in heat exchangerelationship with cooling coils containing a'cold refrigerant suppliedfrom a refrigerant source which includes a compressor and a condensersimultaneously passing hot refrigerant gas from said compressor throughthe cooling coils of the second of said heat exchangers to meltsubstances previously condensed from the high pressure gas;

FORM PC4050 v I USCOMM-DC scam-ps9 W U.S. GOVERNMENT PRlNTlNG OFFICE I9.9 0*38-33 v Page 2 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,750,415 Dated August 7, 1973 Inventor(s) WilfredS. Peuchen; Glenwood K. Pase It is certified that error appears in theaboveidentified patent and that said Letters Patent are hereby correctedas shown below:

(Cl. 7 contd) 2. Terminating the flow of hot refrigerant gas from thecompressor through said cooling coils of the second heat exchanger andreplacing it with a flow of cold regrigerant from thecondenser whilecontinuing to also pass said cold refrigerant through the coils of saidfirst of said heat exchangers in heat exchange relationship with saidhigh pressure gas introduced into said first heat exchanger;

3. Terminating the flow of high pressure gas into the first heatexchanger and directing it instead into said second heat exchanger whereit is passed through in heat exchange relationship cooling coilscontaining cold refrigerant from said refrigerant source; simultaneouslyterminating the flow of cold refrigerant to the cooling coils of saidfirst heat exchanger and passing instead through said coils hotrefrigerant gas from the compressor to melt substances previouslycondensed from the high pressure gas; 7

4. Terminating the flow of hot refrigerant gas from the compressorthrough the cooling coils of said first heat exchanger, and replacing itwith a flow of cold refrigerant from the refrigerant source whilecontinuing to also pass sadxd cold refrigerant through the coils of saidsecond heat exchanger in heat exchange relationship with said highpressure gas;

FORM PO-105O (10-69) USCOMWDC 60.37am

* U.S. GOVERNMENT PRINTING OFFICE: {955 O-365334 K Pa 3 UNITED STATESPATENT OFFICE 98 CERTIFICATE OF CORRECTION 3,750,415 Dated August 7,1973 Wilfred S. Peuchen; Glenwood K. Pase Patent No.

Inventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

(Cl. 7 contd) said high pressure gas being removed from the two heatexchangers separately during each of the four steps of the'process andbeing continuously combined into a common stream and cooled further to,sub-zero temperature by being passed through a third heat exchangerprovided with chilled refrigerant from a refrigeration source.

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMM-DC 60376-P69 LLS. GOVERNMENT PRINTING OFFICE: 19690-366-334 F ORM PO-105O (10-69)

1. An apparatus for continuously cooling and drying a pressurized gascomprising in combination first and second heat exchanger means adaptedfor cooling and condensing moisture from said pressurized gas; a thirdheat exchanger means adapted for further cooling and condensing moisturefrom the gas cooled and dried in said first and second heat exchangers;first and second refrigeration means operatively connected with and eachadapted to provide, in a cyclic system, to said first and second heatexchangers and to said third heat exchanger, respectively, separateflows of hot, pressurized refrigerant gas and cold refrigerant and toreceive a return flow of cold refrigerant gas from said heat exchangers;said first and second heat exchanger means being operatively disposed inparallel and each provided with operatively connected means forregulating And circulating alternating flows of hot refrigerant gas andcold refrigerant from said first refrigeration means through itself andreturning the gas to the refrigeration means; said third heat exchangermeans also being provided with means for regulating and circulatingalternate flows of hot refrigerant gas and cold refrigerant from saidsecond refrigeration means through itself and returning therefrigeration gas to the refrigeration means; said first and second heatexchanger means each being further provided with means operativelyconnected for alternately circulating and regulating a separate flow ofhigh temperature, pressurized gas through itself in heat exchangerelationship with said cold refrigerant and then to said third heatexchanger means where further circulating and regulating means areprovided for conducting said gas through said heat exchanger means inheat exchange relationship with said cold refrigerant provided thereto.2. The apparatus of claim 1 which further comprises preliminary heatexchanger means provided with means operatively connected with saidfirst and second heat exchangers for circulating the flow of cooled,high pressurized gas from said first and second heat exchangers throughitself and then to said third heat exchanger means; said preliminaryheat exchanger means being further provided with operatively disposedmeans for passing the stream of high temperature, pressurized gas fromits source in heat exchange relationship with said cooled gas and thento said first and second heat exchanger means.
 2. Terminating the flowof hot refrigerant gas from the compressor through said cooling coils ofthe second heat exchanger and replacing it with a flow of coldrefrigerant from the condenser while continuing to also pass said coldrefrigerant through the coils of said first of said heat exchangers inheat exchange relationship with said high pressure gas introduced intosaid first heat exchanger;
 3. The apparatus of claim 1 wherein saidrefrigeration means comprises in combination condenser means andcompressor means operatively connected to provide a flow of hot,compressed refrigerant gas to said condenser means and alternately gasfrom said compressor through the cooling coils of the second of saidheat exchangers to melt substances previously condensed from the highpressure gas;
 3. Terminating the flow of high pressure gas into thefirst heat exchanger and directing it instead into said second heatexchanger where it is passed through in heat exchange relationshipcooling coils containing cold refrigerant from said refrigerant source;simultaneously terminating the flow of cold refrigerant to the coolingcoils of said first heat exchanger and passing instead through saidcoils hot refrigerant gas from the compressor to melt substancespreviously condensed from the high pressure gas; to each of said firstand second heat exchangers; said condenser means being further adaptedto receive said hot, compressed refrigerant from said compressor meansand to condense and cool it to a refrigerant liquid; means operativelyconnected to said condenser for regulating and circulating saidrefrigerant liquid to each of said first and second heat exchangers. 4.The apparatus of claim 1 wherein said hot, pressurized gas is air whichemerges from said apparatus at a temperature below 0* F.
 4. Terminatingthe flow of hot refrigerant gas from the compressor through the coolingcoils of said first heat exchanger, and replacing it with a flow of coldrefrigerant from the refrigerant source while continuing to also passsaid cold refrigerant through the coils of said second heat exchanger inheat exchange relationship with said high pressure gas; said highpressure gas being removed from the two heat exchangers separatelyduring each of the four steps of the process and being continuouslycombined into a common stream and cooled further to sub-zero temperatureby being passed through a third heat exchanger provided with chilledrefrigerant from a refrigeration source.
 5. The apparatus of claim 4wherein said air is cooled to -60* F.
 6. The apparatus of claim 1 whichis operatively connected to provide cold, pressurized air to a devicefor blow-molding plastic articles.
 7. A four-stage continuous processfor cooling hot, high pressure gas comprising the steps of:
 8. Theprocess of claim 7 wherein the hot refrigerant gas is pre-cooled in apreliminary heat exchanger in heat exchange relationship with the streamof gas carried off continuously from said heat exchangers which is thendirected to said third heat exchanger.
 9. The process of claim 7 whereinsaid high pressure gas is air which emerges from said third heatexchanger at about -60* F.